To be honest, this sounds like malware, since the problem started after downloading or streaming a movie. IF the vid was downloaded, delete it if the device stays on long enough for you to do that. You should also delete the internet history and cache memory.
You didn't indicate if you could actually turn the tablet completely off. You have to have the device completely powered off to perform a factory reset. The fact that you've uninstalled apps and they came back tells me that the factory reset was unsuccessful or not done properly. If you've been doing this without powering the tablet completely off, that is probably the reason.
Sorry that I can't be more helpful but hopefully this will get you fixed up. ;-)